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Surface Processes and the Hydrosphere Unit Heating the Earth’s Atmosphere Chapter 11 (pg. 352 –385) 11.1: Focus on the Atmosphere: Weather and Climate What is the difference between the weather and climate in Vancouver? Weather: state of the atmosphere at a given time and place. Constantly changing. Climate: the sum of all statistical weather information that helps describe a place or region. Average weather Weather and Climate are described using the same elements: 1) 2) 3) 4) 5) 6) Air Temperature Humidity Type and amount of cloudiness Type and amount of precipitation Air pressure Speed and direction of the wind All of these elements are interconnected and have an effect on each other 11.2: Composition of the Atmosphere Earth’s Atmosphere: Envelope of air between Earth’s surface and Space - Air is a mixture of many different gases and other components - The composition is not constant What is the importance of the components that make up air? a) Nitrogen: Building block of proteins, atmosphere is the major source b) Oxygen: Necessary for cellular respiration c) Carbon Dioxide: Absorbs energy emitted by earth (infrared radiation) = plays a role in heating the atmosphere. Levels are rising = global warming. d) Water Vapour: Humidity varies by location/season. Source for all clouds, precipitation, absorbs heat from Earth/Sun, energy source driving storms. e) Aerosols: Particles kept in the atmosphere by air movement. Condensation surfaces, absorb/reflect incoming solar radiation. f) Ozone: Concentrated in the stratosphere and absorbs UV radiation - Oxygen and Nitrogen are the most abundant but have little or no importance in affecting weather phenomena 11.3: Structure of the Atmosphere -The atmosphere is divided into layers based on fluctuating temperature, pressure and gas composition. -Complete the table below to explore the characteristics of the atmosphere’s layers: Layer Exospohere Height Above Earth 130 + Temperature Conditions Pressure Conditions <10 Thermosphere 80 – 130 -90 - -10 <10 Temp increase due to short wavelength energy solar radiation Mesophere 47 – 80km 0 - -90 <10 Coldest temperatures of any level Least explored region 10km – 47km -60 – 0 10 mb – 300 Increased heat due to ozone layer 10 km 20 - -60 300 – 1000 mb Most of the gases are found here Turbulent air, area where meteorologists focus Stratosphere Trophosphere Other Notes *View Power of the Planet: Atmosphere, 0 to 24:31 minutes. 11.4: Earth-Sun Relationships -Earth’s weather patterns, climates and ocean currents are the products of the unequal distribution of energy from the Sun. -Exploring this idea will draw on many ideas from our Solar System Unit, such as the Earth’s rotation, revolution and the creation of seasons. *Lab Book: Exercise 12: Earth-Sun Relationships 11.5 and 11.6: Heating the Atmosphere Mechanisms of Heat Transfer -In all scenarios heat is always transferred from warmer to colder objects. Conduction: Transfer of energy through matter by molecules colliding. Convection: Transfer of energy by movement/circulation of a substance (e.g. air, water, magma). Creates convection currents. Radiation: Doesn’t require a medium for the transfer of energy. Is how solar energy (visible light, UV radiation, infrared radiation) reaches us through space. Heating the Atmosphere Incoming solar energy can be: a) Redirected: Radiation is bounced off a surface without any energy being absorbed or transmitted. -30% of the solar radiation entering Earth’s atmosphere is returned to space. -The amount of solar radiation reflected by a surface is called its albedo (high albedo = very reflective) -What is Earth’s planetary albedo? 30% -What are some factors affecting albedo? o o o Colour of the surface (dark absorbs more solar radiation) Cloud cover/aerosols Angle of the sun’s rays. b) Transmit: Radiation can pass through substances transparent to certain wavelengths (water, air). The substance does not absorb any energy. c) Absorbed: Gases selectively absorb specific radiation wavelengths, primarily longwave infrared radiation (energy re-radiated from Earth). *Watch the Smart figure on the Ozone Layer *Check out Smartfigure 11.23! Is the Greenhouse Effect a useful or harmful process? Depends on where it is occurring at to what degree: On Earth it is good for keeping warmth in, but if it occurred at a higher rate Earth could be too hot for life (e.g. more Martian). *View Power of the Planet: Atmosphere, 47 minutes to End 11.7: Human Impact on the Atmosphere’s Composition CO2 Emissions -One of the most significant ways humans are impacting the atmosphere is through the addition of CO2. -Using information from section 11.5 and 11.6, what are the potential consequences of increasing the CO2 concentration in the atmosphere be? CO2 absorbs infrared radiation, preventing it from leaving Earth. This would have significant consequences for the atmosphere’s temperature: essentially it would produce a magnified greenhouse effect. -What natural and human activities add CO2 to the atmosphere? Natural: Forest fires, respiring Burning fossil fuels (coal, natural gas, pertroleum), deforestation (burning vegetation, removing trees that can remove CO2 from atmosphere) -Check out the National Geographic Warming Effects Map and write down at least 5 negatives and 5 positive implications of global warming http://environment.nationalgeographic.com/environment/global-warming/gw-impacts-interactive/ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ 11.8: Air Temperature Data -Explore this concept through Exercise 13 in the lab book. Do not complete section 13.7 or the Lab report at the end of the exercise. 11.9: Air Why do Temperatures Vary? -Air temperatures vary by location and season because of the influence of temperature control variables. -In a previous section we mentioned that the largest cause of air temperature variations was differences solar radiation received (e.g. Due to latitude, angle of insolation), but there are also other important factors: a) Land vs. Water: Explore this idea by conducting Experiment: Differential Heating of Land and Water in Activity 13B. b) Altitude: Air temp cools by 6.5 C/km in the troposphere (due to presence of gases and distance from Earth’s surface c) Geographic Position: Windward coasts have a climate moderated by oceans (cool summers, mild winters); Leeward coasts have a continental climate (warm summers, cold winters). Spokane has mountains blocking the ocean winds, so has a continental climate. d) Cloud Cover and Albedo: Watch Smartfigure 11.36 to examine the effect of these variables on air temperature. Clouds reflect solar radiation and prevent most of it from reaching the Earth’s surface = mild day. By the same process, clouds can also prevent infrared radiation from escaping into space at night = warm nights. 11.10: World Distribution of Temperature -Explore this concept through Exercise 13.